Method of the arc welding and deposition of metals in vacuum

ABSTRACT

A method of the arc welding and deposition of metals in vacuum by means of a consumable electrode, in which for the purpose of providing the stable arcing process between the electrode wire and the workpiece, the arc is stabilized by shielding the current-carrying parts of one of the electrodes with the aid of a metal envelope having a charge corresponding to the charge of the other electrode.

United States Patent [72] Inventors Nikolai Alexandrovich Olshansky [56] Reference Cited agonoloslilnggstlzovskaya ulltsa 6, Kv. 2, UNITED STATES PATENTS oscow, Alexandra vhdimimvna Mordvimsevd, llvfigler 219/131 deceased. lite 0' Moscow, UIS.S.R. 0 Son et a 2 1 X 11/1966 Allen et a1. 219/135 (Alexander Mordvlntsev Leonlde, 3 43' 390 3/1969 Moinz mtg/135 X a m i t or, Mira kv. I a Moscow, U.S.S.R.) Primary Examiner-J. V. Truhe [21] Appl. No. 836,669 Assistant Examiner-C. L. Albritton [22] Filed June 25, 1969 Anarney- Waters, Roditi. Schwartz & Nissen [45] Patented Aug. 17, 1971 [54] METHOD OF THE ARC WELDING AND 1 DEPOSITION O METALS IN VACUUM I ABSTRACT: A method of the arc welding and deposition of Chimsflnnming Figs? metals in vacuum by means of a consumable electrode, in 52 0.5. CI. 219/137, which for the purpose of Providing e stable arcing pwcchs 219/130 between the electrode wire and the workpiece. the are is sta- [51] Int. Cl .L 823k 9/10 hilized by shielding the current-carrying P of one of the 501 7 Field of Search 219 13o, cleclwdes Wilh thwid of a metal envclhpe having h charge corresponding to the charge of the other electrode.

PATENTEU M] 11911 3,600,549

FIG. 2

METHOD OF THE ARC WELDING AND DEPOSITION F METALSINVACUUM T The present invention relates to welding practice, and more particularly, it concerns methods of arc welding and deposition of metals in vacuum. The method according to the invention may be used to advantage for the welding and deposition of all metals and alloys, especially of light and active metals and alloys.

Widely used in the prior art is a method for the arc welding and deposition of metals in inert gases, for example, argon.

This method has proved to be successful when welding metals having a comparatively small thickness (10-15 mm.), but if the thickness increases, the mechanical properties of the weld metal and, therefore, of the welded joint deteriorate. Also known in the prior art is a method of electroslagwelding of metals having a thickness greater than 20 mm. Nevertheless, the electroslag' welding of light and active metals does not provide for obtaining the properties of the metal of the welded joint similar to those of the basemetal. The main reasons which account for a poor quality of the welded joint produced with the aid of the-known'met'hods, consist ininsufficient protection of the metal of the welded joint, a great number of welding beads (if the argon arc welding is employed), and the difficulties encountered when selecting a flux (when the electroslag welding is employed).

ln order to eliminate the above-saiddisadvantages, attempts have been made to effect the process. of arc welding in vacuum; however, this method does not provide for a stable arc discharge in vacuum of 10' mm. mercury column.

To provide for a stable arc discharge attempts have been made to admit an inert gas into the arcing zone or to use magnetic stabilization of the process. The admission of the inert gas into the arcing zone allows the arc to be stabilized: yet, this reduces the efiiciency of the vacuum protection and deteriorates the electrical and economic characteristics of the process (theidepthof fusion, deposition rate-factor). The vacuum welding with the magnetic stabilization of the arc is a .pure vacuum method to be resorted to during the welding of materials having rather a small thickness (-less than 5-6 mm.) by means of n'o'nc'onsumable electrodes. When using a nonconsumable electrode, particularly if a weldingcur rentnexceeds 300 amperes, when mm., especially when welding ferromagnetic metals, it isnot possible to induce a stabilizing magneticfield. u v

dnobject of the present invention istoelirtrinatethe abovementioned disadvantages. I I

- The specific object of the ,inven'tionis to provide such a method of the arc welding and ,deposition of metals in vacuum, which would make itpossibleto effect the process'of welding heavy gaugemetalsby meansof a consumable electrode with dependable stabilization of thearcing process.

This objectis attain'ed'by providing a method of'the welding and deposition of metals in vacuum bymeans'ofaconsumable electrode with astabilization of thearcing in-which, according to the invention, the stabilizationof ,the arcing process is provided by shielding the current-carrying parts of --one of the electrodes, for example the.wire,with the aid-of a metal e'n velopehaving a charge corresponding -to thatr0f-the other electrode, for example of the article being welded; The presence of the metal envelope ensures stable arcing only between'the electrode wireandthearticle being-weldedand prevents developmentof'the parasitic? arcing process making-root welds of metals having a thickness exceeding .20

The purposed process is carried into effect in a vacuum chamber 1 (FIG. 1) accommodating a workpiece 3 to be welded, which is mounted on a movable table 2 electrically connected to the chamber and negativeterminal of the current source, the workpiece 3, being one of the welding electrodes.

' The welding wire is fed into the upper portion of the vacuum chamber by means of a head 4. The welding wire is supplied with the welding current through a tip 6. The input of the tip 6 and the welding wire are electrically insulated from the chamber by means of an insulator 7 which at the same time is a sealing device, whereas the tip is connected to the positive terminal of the power source.

To stabilize the arcing process and to eliminate parasitic" discharges between the workpiece being welded and the tip, these members are shielded by a metal envelope 8 (FIGS. 1 and 2) having an opening in the lower portion for passing the welding wire. The metal envelope and the tip are connected to an additional low power supply source so that the polarity of the workpiece being welded and that of the metal are the same. In this case, the voltage of the additional power supply source may be varied within a wide range.

The proposed method may be also effected without using an additional power source.

In this case, the parasitic discharges are eliminated due to the fact that when striking the electric arc, the metal envelope stores an electric charge whose polarity is similar to that of the workpiece. I

According to the proposed method, the workpiece with the edges, having been prepared in the usual manner, is placed on the table L -mounted in the vacuum chamber.

The chamber is hermetically sealed and provided with a vacuum of at least 10 mm. mercury column. Thereafter, the electric arc is stricken between the welding wire and the workpiece. ln this case, the metal of the wire is melted down and deposited onto the workpiece. v

The welded workpieces manufactured with the aid of the vacuum welding process feature high mechanical properties, particularly, when welding active and. refractory metals, because, as it is known, the' rnetal being melted in a vacuum contains smaller proportion of gases and impurities.

Thextests of the-proposed method used for welding and deposition of aluminum and titanium alloys have shown that the process characteristics of the vacuum arc welding are superiorto the same characteristics of the argon arc welding in many respects. For example, thefusion and deposition rate factors during the-vacuum are welding are increased by a factor of five; the-metal ofthe welded joint produced in a vacuum of 5.10 mm; mercury column contains dissolved gases and .other'impu'rities in an amount by as much as 2 to 3 times lower than that attainable during the other processes of welding,

during-the welding-of titanium alloys having the thickness within the range of 10 to "50mm, the obtained impact value of the 'weld metal considerably exceeds theimpact strength of the base metal.

Weclaim:

l. A'method of arc welding and depositing metals in a vacuum comprising providing a workpiec'eand a consumable electrode --in-a vacuum opposite one another in spaced relation. said workpiece constituting an electrode, producing respective charges in the workpiece and consumable electrode -'to provide an electric arc therebetween, shieldingthe consumable electrode with a metallic envelope having op- ,posite open'endsthrough which the consumable electrode is movable-and insulated'therefrom, and producing in the metalic envelope a charge corresponding in polarity to the charge in the workpiece.

4. A method as claimed in claim 3 wherein the metallic envelope and the consumable ;electrode are connected to the negative and positive poles respectively of the independent power supply and wherein the workpiece is charged negative- 1y. 

1. A method of arc welding and depositing metals in a vacuum comprising providing a workpiece and a consumable electrode in a vacuum opposite one another in spaced relation, said workpiece constituting an electrode, producing respective charges in the workpiece and consumable electrode to provide an electric arc therebetween, shielding the consumable electrode with a metallic envelope having opposite open ends through which the consumable electrode is movable and insulated therefrom, and producing in the metalic envelope a charge corresponding in polarity to the charge in the workpiece.
 2. A method as claimed in claim 1 wherein the charge produced in the metallic envelope is produced by the electric arc and stored in the metallic envelope.
 3. A method as claimed in claim 1 including connecting the consumable electrode and the metallic envelope to an independent power supply for producing the charge in the metallic envelope.
 4. A method as claimed in claim 3 wherein the metallic envelope and the consumable electrode are connected to the negative and positive poles respectively of the independent power supply and wherein the workpiece is charged negatively. 